Netflix payment method gift card?

I did not find anyone with my problem on the internet, that's why I'm asking jz here.Also…

… If I want to set up a Netflix subscription, I have to logically specify a payment method. Now the problem: Since I have no KOnto (such as credit account, PayPal…), I would like to pay with these gift cards.

I read that you have to specify an alternative payment method for the card? Is that correct?

If it is not so, how do I do it with the remaining balance of a card? Can I redeem multiple vouchers at the same time, or transfer that amount to another card?

Please do not be a moralist, and say that Netflix is only 18, which is true in part, but why give a parental lock when it's over 18?

Preliminary: Netflix is from 18.

I would instead of these voucher cards get a prepaid credit card, there are at gas stations and Co - recharge like a mobile phone card.

I'm only 14

Well, that changes my answer but nothing.